Liu Q, Ji X, Breitman M L, Hitchcock P F, Swaroop A
Division of Molecular and Developmental Biology, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
Oncogene. 1996 Jan 4;12(1):207-11.
Proteins of the Maf/Nrl subfamily of bZIP transcription factors are involved in the regulation of tissue-specific gene expression. The Nrl gene, initially identified from a subtracted retinal library, is expressed in all cell layers of the adult retina, including photoreceptors. The Nrl protein has high sequence homology with Maf proteins, binds to an AP-1 like sequence element, and in photoreceptors appears to be involved in regulating the expression of rhodopsin. In the present study, we investigated the expression of Nrl in the developing and adult mouse using in situ hybridization and RT-PCR. We demonstrate that beginning at embryonic day 12.5 Nrl is expressed throughout the developing central and peripheral nervous system, with the exception of the nasal epithelium. The spatial pattern of hybridization suggests that Nrl is transcribed in post-mitotic, differentiating neurons, the developing cephalic mesenchyme and lens. Nrl expression is downregulated postnatally in the brain, and becomes restricted to neocortex and brainstem in the adult. High levels of Nrl transcripts, however, persist in the mature photoreceptors and other retinal neurons. Our studies suggest a role for the Nrl protein in neuronal differentiation and in mature neurons of the adult retina.
bZIP转录因子的Maf/Nrl亚家族蛋白参与组织特异性基因表达的调控。Nrl基因最初是从一个消减视网膜文库中鉴定出来的，在成年视网膜的所有细胞层中都有表达，包括光感受器。Nrl蛋白与Maf蛋白具有高度的序列同源性，能与一个类似AP-1的序列元件结合，并且在光感受器中似乎参与视紫红质表达的调控。在本研究中，我们使用原位杂交和RT-PCR技术研究了Nrl在发育中和成年小鼠中的表达情况。我们证明，从胚胎第12.5天开始，Nrl在整个发育中的中枢和外周神经系统中表达，但鼻上皮除外。杂交的空间模式表明，Nrl在有丝分裂后分化的神经元、发育中的头部间充质和晶状体中被转录。出生后，Nrl在大脑中的表达下调，在成年后局限于新皮层和脑干。然而，高水平的Nrl转录本在成熟的光感受器和其他视网膜神经元中持续存在。我们的研究表明Nrl蛋白在神经元分化和成年视网膜的成熟神经元中发挥作用。
